Please check your CloudStorageDemo. With every connect of DropBox I have to authenticate the access. You don't need to close the app. Only connect to DropBox, and disconnect. The next connect you have to authenticate again!
Btw. I changed the step by step instructions LoadTokens, Resfresh a.s.o to Storage.Connect....
The resdat of HttpsPost (TestTokens) has the following value:
'Error in call to API function "users/get_current_account": Bad HTTP "Content-Type" header: "application/x-www-form-urlencoded". Expecting one of "application/json", "application/json; charset=utf-8",'...